That works well for small repos or a few repos but if you want to find all cc files, at all release branch's, in your entire company and check for some exploit it is helpful to have a VFS. Makes it so you could also support N SCMs through one API. You just need to make a new VFS.
Needing to tie into a specific API (like codesearch) couples you to the specific storage backend (Github). If you build your software to operate on a POSIX-y file system, you can support anything that shows up as a file system. For example: A local working tree of files, an NFS share, or now a remote git repository.
